194 THE INDIA-RUBBER OF THE AMAZON. 
Some who began by cutting down the trees, found that in this way 
they obtained much less milk than by successive tappings of the same 
tree, besides that the work was harder, and it was necessary continually 
to shift their sphere of operations. I am glad therefore that this kill- 
ing of the hen to get at the golden eggs has been abandoned. 
Most seringueiros follow the old mode of drying the milk by smoke, 
applied to successive coatings on a mould. Some have filled a small 
square box with the milk, and allowed it to coagulate; but, as the 
milk does not become solid until the end of ten days or more, and the 
mass then requires to be cut into thin slices, and subjected to heavy 
pressure (such as it is difficult to obtain here), in order to free it from 
— the water and air collected in cells within its substance, this mode 1s 
by no means popular, 
Tt is found that the addition of a small quantity of alum accelerates 
the coagulation of the milk. Ammonia has a contrary effect, and 1s 
accordingly useful when the milk is required to be kept some time in a 
liquid state. 
When the trees are flowering, nearly all the milk goes to the nourish- 
ment of the flowers, and scarcely any can be obtained from the trunk, 
while if a panicle be wounded the milk starts out in large drops. . It is 
customary to leave the trees untouched for a few months in the year, 
from the epoch of flowering until the fruit has attained its full size. 
About Para, the collection of seringa seems limited to the dry season— 
June to December. On the upper Rio Negro, the seringa-trees flower 
from November to the end of January; and when I started from San 
Carlos on November 23rd, little milk was to be obtained. 
"The species from which rubber is extracted on the upper Rio Negro 
and lower Casiquiare are two, Siphonia lutea, Spruce (Journ. of Bot. 
. vi. 370), and S. brevifolia, Spruce (3139 to Bentham); known respec- 
tively as the long-leaved and short-leaved seringa. The former yields 
most milk, but neither is so productive as the seringa of Para (Siphonia 
_ Brasiliensis, Willd.). Both are straight, tall, and not very thick trees, 
with smoothish thin bark, and yellow very odoriferous flowers, while 
the other species have mostly purplish flowers. I suppose their average 
height may be about 100 feet. T cut down a tree of S. brevifolia neat 
‘San Carlos which measured 110 feet. I first saw and gathered S. lutea 
in the mouth of the Uaupés; and as I came down the Rio Negro in. 
December, 1854, I found a rancho erected on the spot, and a person 
